AV News reported last year that the folk-rock supergroup Crosby, Stills, Nash and Young might put aside the feuding that has plagued the band since the early 1970s and reunite because they “hate Trump even more than they hate each other.” That reunion has not happened yet, but it looks like the Democratic Party may be getting the band back together. And disgust at Donald Trump may be all America’s left needs to keep itself intact — for now.

Democrat Conor Lamb, who looks to have won a special election in a western Pennsylvania congressional district Trump carried by about 20 percentage points and Mitt Romney by 17, would not pass anyone’s purity test.

Lamb managed to present himself as pro-gun and pro-life, though he supports the Manchin-Toomey background check bill and opposes a 20-week abortion ban. He has successfully courted union voters, who had long backed former Republican congressman Tim Murphy, despite refusing to support the core labor demand of a $15 minimum wage. And he’s won the backing and small-dollar donations of Democrats from across the nation while vowing he would not vote for Nancy Pelosi as House speaker.

Conor Lamb, the Democratic candidate for the March 13 special election in Pennsylvania's 18th Congressional District celebrates with his supporters at his election night party in Canonsburg, Pa., early Wednesday, March 14, 2018. A razor's edge separated Lamb and Republican Rick Saccone early Wednesday in their closely watched special election in Pennsylvania, where a surprisingly strong bid by first-time candidate Lamb severely tested Donald Trump's sway in a GOP stronghold.(Photo: Gene J. Puskar, AP)

Lamb’s artful “baby splitting” could have effectively branded him as the sort of moderate Democrats are supposed to be driving from their ballot slots. But instead, he should be praised as the kind of candidate the left needs to embrace, or at least tolerate, in order to succeed in their critical effort to take at least one chamber of Congress.

When Democrats focus their rage at Trump into amassing donations and motivating volunteers and then run against the actual Republican they’re facing, they’ve been winning, even seats they shouldn’t win. That worked in Virginia, Alabama and now in Rust Belt. And it’s a formula that could be the tidal force behind a blue wave in November.

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Yes, if new congressional maps in Pennsylvania stand, Democrats can target 25 Republican House district where Hillary Clinton got more votes than Trump — enough to win the House without having to woo new voters. But even when your party is led by the least popular new president in polling history, incumbency has its advantages. Maps have been gerrymandered so the GOP could probably lose the total popular vote by three times Trump's losing margin and still keep its House majority.

While voters don’t seem to be in love with the GOP’s tax cuts, even in a very Trump district, GOP donors are big fans of their huge payoffs. And they’re rewarding their workforce. Outside groups backing Republican Rick Saccone in the Pennsylvania 18 special election outspent those supporting Democrats by $10.7 million to $2 million.

And then there’s the Senate. Democrats are defending 25 seats to the GOP’s eight, 10 of them in states Trump won. Unless Democrats manage to put several dozen seats in play, Republicans could keep the House and add several seats in the Senate.

This would be a disaster from a policy standpoint. But even beyond that, based on what we've seen over the last year, it would be an irreversible nightmare of historic proportions.

If Republicans kept their House and Senate majorities, it would vindicate their focus on obstructing investigations into the Trump administration instead of digging into what is already the most felony-ridden presidential campaign in living memory, and the first president who refuses to divest from business interests that continue to occupy at least a quarter of his time.

If Democrats believe the more fevered warnings they’ve been making — that Trump is a historic threat to democracy, that the GOP Congress is more interested in obstructing justice for him than investigating him, that two more years of this will fry what’s left of our nerve endings — the upcoming elections aren’t just elections. They are a national emergency: the only possible way to put a keen eye on corruption, the Census and foreign intrusion in our elections.

That isn’t to say Democrats shouldn’t make demands on their candidates and run competitive primaries. There are over 110 GOP-held districts that are more Democratic than Pennsylvania’s 18th. Few nominees will triangulate to the degree Lamb has. But in a historic crisis such as what we face now, differences of opinion shouldn’t be read as differences of principle. And true anger needs to end up focusing on defeating Republicans whenever there’s a chance to defeat Republicans.

Then, when some semblance of checks and balances is restored and the House begins actual oversight of the Trump administration, Democrats can turn to battling out what agenda they will run on in 2020.

The special election on Tuesday was an anomaly in several ways. A Republican congressman resigned after urging his mistress to have an abortion. Lamb avoided a tough primary as party insiders selected him and his uninspired opponent. And the seat will not likely even exist next year.

But if Democrats take what they’ve learned here, anything is possible.

Jason Sattler, a writer based in Ann Arbor, Mich., is a member of USA TODAY’s Board of Contributors and host of The Sit and Spin Room podcast.